Load partitioning and evidence of deformation twinning in dual-phase fine-grained zr-2.5%Nb alloy.

In situ neutron diffraction loading experiments were carried out on a cold-rolled dual-phase (a-phase, '"' 10% b-phase) Zr–2.5%Nb alloy at room temperature. The specimens were cut at different angles from the rolling direction (RD) towards the transverse direction (TD), thus the loading axis changes gradually from the rolling to transverse direction. Due to the strong texture of the studied alloy, and unidirectional nature of deformation twinning, the changing loading direction with respect to initial texture has a significant impact on the collaborative slip-twinning deformation mode in the hexagonal close-packed (hcp) a-phase. The present neutron diffraction results provide direct evidence of {1 - 1.2}/1 - 1. - 1S ‘‘tensile’’ twins in the a-phase of dual-phase Zr–2.5%Nb alloy at room temperature. Additionally, TEM analysis was employed to confirm the presence of ‘‘tensile’’ twins, and determine if other type of twins were present. It is further clear from the neutron diffraction results that applied load is gradually transferred from the plastically softer a-phase to the plastically harder b-phase which acts as a reinforcing phase having a yield strength in the range 750–900 MPa depending on the loading direction

Plant responses to geminivirus infection: guardians of the plant immunity

BackgroundGeminiviruses are circular, single-stranded viruses responsible for enormous crop loss worldwide. Rapid expansion of geminivirus diversity outweighs the continuous effort to control its spread. Geminiviruses channelize the host cell machinery in their favour by manipulating the gene expression, cell signalling, protein turnover, and metabolic reprogramming of plants. As a response to viral infection, plants have evolved to deploy various strategies to subvert the virus invasion and reinstate cellular homeostasis.Main bodyNumerous reports exploring various aspects of plant-geminivirus interaction portray the subtlety and flexibility of the host-pathogen dynamics. To leverage this pool of knowledge towards raising antiviral resistance in host plants, a comprehensive account of plant's defence response against geminiviruses is required. This review discusses the current knowledge of plant's antiviral responses exerted to geminivirus in the light of resistance mechanisms and the innate genetic factors contributing to the defence. We have revisited the defence pathways involving transcriptional and post-transcriptional gene silencing, ubiquitin-proteasomal degradation pathway, protein kinase signalling cascades, autophagy, and hypersensitive responses. In addition, geminivirus-induced phytohormonal fluctuations, the subsequent alterations in primary and secondary metabolites, and their impact on pathogenesis along with the recent advancements of CRISPR-Cas9 technique in generating the geminivirus resistance in plants have been discussed.ConclusionsConsidering the rapid development in the field of plant-virus interaction, this review provides a timely and comprehensive account of molecular nuances that define the course of geminivirus infection and can be exploited in generating virus-resistant plants to control global agricultural damage

Multifaceted role of geminivirus associated betasatellite in pathogenesis

Begomoviruses have emerged as a group of plant pathogens that cause devastating diseases in a wide range of crops in tropical and subtropical regions of the world. Betasatellites, the circular single-stranded DNA molecules with the size of almost half of that of the associated helper begomoviruses, are often essential for the production of typical disease symptoms in several virus-host systems. Association of betasatellites with begomoviruses results in more severe symptoms in the plants and affects the yield of numerous crops leading to huge agroeconomic losses. βC1, the only protein encoded by betasatellites, plays a multifaceted role in the successful establishment of infection. This protein counteracts the innate defence mechanisms of the host, like RNA silencing, ubiquitin-proteasome system and defence responsive hormones. In the last two decades, the molecular aspect of betasatellite pathogenesis has attracted much attention from the researchers worldwide, and reports have shown that βC1 protein aggravates the helper begomovirus disease complex by modulating specific host factors. This review discusses the molecular aspects of the pathogenesis of betasatellites, including various βC1-host factor interactions and their effects on the suppression of defence responses of the plants

Effect of He Plasma Exposure on Recrystallization Behaviour and Mechanical Properties of Exposed W Surfaces—An EBSD and Nanoindentation Study

Fusion reactors are designed to operate at extremely high temperatures, which causes the plasma-facing materials to be heated to 500 °C to 1000 °C. Tungsten is one of the target design materials for the plasma-facing diverter components in Tokamak designs, such as ITER, because of its excellent high-temperature strength and creep properties. However, recrystallization due to high temperatures may be detrimental to these superior mechanical properties, while exposure to He plasma has been reported to influence the recrystallization behaviour. This influence is most likely due to the Zener effect caused by He bubbles formed near the surface, which retard the migration of grain boundaries, while at the same time modifying the surface microstructure. This paper reports a study of the effect of plasma exposure at different sample temperatures on the recrystallization behaviour of W at different annealing temperatures. The characterization after plasma exposure and annealing is pursued through a series of post-exposure annealing, followed by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) characterization and nanoindentation to determine the mechanical properties. Here, it is shown that the hardness is closely related to the recrystallization fraction, and that the plasma exposure at a sample temperature of 300 °C slows down the recrystallization more than at higher sample temperatures of 500 °C and 800 °C. Atomic force microscopy (AFM) was subsequently used to determine any changes in pile-up height around the nanoindents, to probe any indication of changes in hardenability. However, these measurements failed to provide any clear evidence regarding this aspect of mechanical behaviour